Runtime configuration: Performance

  • Memory related:

    • shared_buffers: amount of shared memory blocks to use (1 block = 8K)

    • wal_buffers: number of blocks in shared memory reserved for write ahead logging (WAL)

    • sort_mem: amount of memory, in KB, a single sort can use before backing on to disk (non-trivial queries often require several sorts!)

    • vacuum_mem: amount of memory, in KB, available to VACUUM before backing on to disk


    • max_fsm_relations: (max) number of relations for which free space will be tracked

    • max_fsm_pages: (max) number of disk pages for which free space will be tracked

    • memory usage for default FSM: 70868 bytes on i386; grows by 4-5K per 100 relations, 650 bytes per 100 pages (see freespace.c:FreeSpaceShmemSize() for algorithm)
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